Lithium transition metal phosphate (LiMPO4, where M denotes a transition metal; hereinafter referred to as LMP) is a promising cathode active material for lithium secondary batteries.
As a method of preparing LMP, for example, a solid phase method and a sol-gel method are used.
In a solid phase method, solid-phase reactants are mixed and heated to prepare LMP. However, due to the high heating temperature, it is difficult to obtain uniform nanoparticles. Also, to manufacture such uniform nanoparticles, micro-particle powder reactants are required. Accordingly, a dependency on reactants is high and thus economic efficiency reduces.
Moreover, the solid phase method involves thermal treatment in a reducing condition, which requires particular attention. Due to a low electric conductivity of LMP, to realize battery characteristics, surfaces of LMP particles need to be coated with a conductive material. However, this surface coating is difficult to be implemented with the solid phase method.
In a sol-gel method, a metal alkoxide source material is transformed into a sol state and then gelled through condensation reaction, followed by drying and heating to prepare LMP. However, reactants used in this method are expensive and also, this method is based on an organic solvent. Accordingly, manufacturing costs are high.